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Method of Etching Silicon Carbide

IP.com Disclosure Number: IPCOM000094900D
Original Publication Date: 1965-Jul-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Ebert, E: AUTHOR

Abstract

Silicon carbide monocrystalline wafers, used in fabricating semiconductor components, cannot be etched by the otherwise customary methods because of the high chemical resistance of that material. Although it is possible to etch silicon carbide with gaseous fluorine, the fluorine compounds suitable as etchants, such as ClF(3), are difficult to handle. This is primarily because of the high aggressiveness of the decomposition products.

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Method of Etching Silicon Carbide

Silicon carbide monocrystalline wafers, used in fabricating semiconductor components, cannot be etched by the otherwise customary methods because of the high chemical resistance of that material. Although it is possible to etch silicon carbide with gaseous fluorine, the fluorine compounds suitable as etchants, such as ClF(3), are difficult to handle. This is primarily because of the high aggressiveness of the decomposition products.

A useful method is realized by using nitrogen tri-fluoride NF(3). This gas is inert at room temperature and does not attack the reaction vessels which mostly consist of quartz. It is easily liquefiable and can thus be stored in large quantities.

The SiC wafer to be etched is heated to approximately 1000 degrees C. in a reaction vessel and exposed to the NF(3) gas flow to which other inert gases can be admixed with the exclusion of oxygen. At the surface of the wafer, the NF(3) gas is pyrolytically decomposed. The nascent fluorine so produced serves to accelerate the etching effect. Moreover, it is possible to etch only selected areas of the wafer, by local heating, e.g., an electron beam.

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